Isaac Khader / htu21d_for_weather_shield

htu21d_for_weather_shield

Dependents:   SPARKFUN_WEATHER_SHIELD

Fork of htu21d by Kevin Braun

htu21d.cpp@1:d3ed713f8354, 2014-05-15 (annotated)

Committer:
loopsva
Date:
Thu May 15 19:12:11 2014 +0000
Revision:
1:d3ed713f8354
Parent:
0:2dab43acb3a4
Child:
2:8fbe84ed61e6
Added serial number access structure. Cleaned up documentation.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
loopsva 0:2dab43acb3a4 1 /**
loopsva 1:d3ed713f8354 2 HTU21D / HPP828E031 driver for mbed.
loopsva 1:d3ed713f8354 3 - Includes RTOS hooks if RTOS is detected during compile.
loopsva 0:2dab43acb3a4 4 Author: Kevin Braun
loopsva 0:2dab43acb3a4 5 **/
loopsva 1:d3ed713f8354 6
loopsva 0:2dab43acb3a4 7 #include "htu21d.h"
loopsva 0:2dab43acb3a4 8
loopsva 0:2dab43acb3a4 9 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 10 extern Mutex MutexI2cWait;
loopsva 0:2dab43acb3a4 11 #endif
loopsva 0:2dab43acb3a4 12
loopsva 0:2dab43acb3a4 13 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 14 //Contstructor
loopsva 0:2dab43acb3a4 15
loopsva 0:2dab43acb3a4 16 htu21d::htu21d(PinName sda, PinName scl) : _i2c(sda, scl) {
loopsva 1:d3ed713f8354 17 _i2c.frequency(400000);
loopsva 1:d3ed713f8354 18 }
loopsva 1:d3ed713f8354 19
loopsva 1:d3ed713f8354 20 htu21d::htu21d(PinName sda, PinName scl, int i2cFrequency) : _i2c(sda, scl) {
loopsva 1:d3ed713f8354 21 _i2c.frequency(i2cFrequency);
loopsva 0:2dab43acb3a4 22 }
loopsva 0:2dab43acb3a4 23
loopsva 0:2dab43acb3a4 24 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 1:d3ed713f8354 25 //Destructor
loopsva 0:2dab43acb3a4 26
loopsva 0:2dab43acb3a4 27 htu21d::~htu21d() {
loopsva 0:2dab43acb3a4 28 }
loopsva 0:2dab43acb3a4 29
loopsva 0:2dab43acb3a4 30 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 31 //Perform a soft reset on the HTU21D. REturn of 1 = ok, 0 = timeout.
loopsva 0:2dab43acb3a4 32
loopsva 0:2dab43acb3a4 33 int htu21d::softReset() {
loopsva 0:2dab43acb3a4 34
loopsva 0:2dab43acb3a4 35 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 36 MutexI2cWait.lock();
loopsva 0:2dab43acb3a4 37 #endif
loopsva 0:2dab43acb3a4 38
loopsva 0:2dab43acb3a4 39 int htu21 = 0;
loopsva 0:2dab43acb3a4 40 _i2c.start();
loopsva 0:2dab43acb3a4 41 htu21 = _i2c.write(HTU21Di2cWRITE); //i2c, 1 = ack
loopsva 0:2dab43acb3a4 42 if(htu21 == 1) {
loopsva 0:2dab43acb3a4 43 _i2c.write(HTU21DRESET); //soft reset, must wait 15mS
loopsva 0:2dab43acb3a4 44 _i2c.stop();
loopsva 1:d3ed713f8354 45 wait_ms(16); //must wait a least 15mS for reset to finish
loopsva 1:d3ed713f8354 46 htu21d::getSNReg(); //go load up the s/n registers
loopsva 0:2dab43acb3a4 47 }
loopsva 1:d3ed713f8354 48
loopsva 0:2dab43acb3a4 49 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 50 MutexI2cWait.unlock();
loopsva 0:2dab43acb3a4 51 #endif
loopsva 0:2dab43acb3a4 52
loopsva 0:2dab43acb3a4 53 return(htu21);
loopsva 0:2dab43acb3a4 54 }
loopsva 0:2dab43acb3a4 55
loopsva 0:2dab43acb3a4 56 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 57 //Get the HTU21D user register. Returns 8 bit register.
loopsva 0:2dab43acb3a4 58
loopsva 0:2dab43acb3a4 59 uint8_t htu21d::getUserReg() {
loopsva 0:2dab43acb3a4 60
loopsva 0:2dab43acb3a4 61 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 62 MutexI2cWait.lock();
loopsva 0:2dab43acb3a4 63 #endif
loopsva 0:2dab43acb3a4 64
loopsva 0:2dab43acb3a4 65 int htu21 = 0;
loopsva 0:2dab43acb3a4 66 uint8_t htu21data = 0;
loopsva 0:2dab43acb3a4 67 _i2c.start();
loopsva 0:2dab43acb3a4 68 htu21 = _i2c.write(HTU21Di2cWRITE); //i2c, 1 = ack
loopsva 0:2dab43acb3a4 69 if(htu21 == 1) {
loopsva 0:2dab43acb3a4 70 _i2c.write(HTU21DREADUSER);
loopsva 0:2dab43acb3a4 71 _i2c.start();
loopsva 0:2dab43acb3a4 72 htu21 = _i2c.write(HTU21Di2cREAD);
loopsva 0:2dab43acb3a4 73 htu21data = _i2c.read(0);
loopsva 0:2dab43acb3a4 74 _i2c.stop();
loopsva 0:2dab43acb3a4 75 }
loopsva 0:2dab43acb3a4 76
loopsva 0:2dab43acb3a4 77 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 78 MutexI2cWait.unlock();
loopsva 0:2dab43acb3a4 79 #endif
loopsva 0:2dab43acb3a4 80
loopsva 0:2dab43acb3a4 81 return(htu21data);
loopsva 0:2dab43acb3a4 82 }
loopsva 0:2dab43acb3a4 83
loopsva 0:2dab43acb3a4 84 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 85 //Turn ON the heater the HTU21D user register.
loopsva 0:2dab43acb3a4 86
loopsva 0:2dab43acb3a4 87 int htu21d::heaterOn() {
loopsva 0:2dab43acb3a4 88 uint8_t htu21data = htu21d::getUserReg();
loopsva 0:2dab43acb3a4 89 htu21data |= HTU21DHEATER;
loopsva 0:2dab43acb3a4 90
loopsva 0:2dab43acb3a4 91 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 92 MutexI2cWait.lock();
loopsva 0:2dab43acb3a4 93 #endif
loopsva 0:2dab43acb3a4 94
loopsva 0:2dab43acb3a4 95 int htu21 = 0;
loopsva 0:2dab43acb3a4 96 _i2c.start();
loopsva 0:2dab43acb3a4 97 htu21 = _i2c.write(HTU21Di2cWRITE); //i2c, 1 = ack
loopsva 0:2dab43acb3a4 98 if(htu21 == 1) {
loopsva 0:2dab43acb3a4 99 _i2c.write(HTU21DWRITEUSER);
loopsva 0:2dab43acb3a4 100 htu21 = _i2c.write(htu21data);
loopsva 0:2dab43acb3a4 101 _i2c.stop();
loopsva 0:2dab43acb3a4 102 }
loopsva 0:2dab43acb3a4 103
loopsva 0:2dab43acb3a4 104 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 105 MutexI2cWait.unlock();
loopsva 0:2dab43acb3a4 106 #endif
loopsva 0:2dab43acb3a4 107
loopsva 0:2dab43acb3a4 108 return(htu21);
loopsva 0:2dab43acb3a4 109 }
loopsva 0:2dab43acb3a4 110
loopsva 0:2dab43acb3a4 111 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 112 //Turn OFF the heater the HTU21D user register.
loopsva 0:2dab43acb3a4 113
loopsva 0:2dab43acb3a4 114 int htu21d::heaterOff() {
loopsva 0:2dab43acb3a4 115 uint8_t htu21data = htu21d::getUserReg();
loopsva 0:2dab43acb3a4 116 htu21data &= ~HTU21DHEATER;
loopsva 0:2dab43acb3a4 117
loopsva 0:2dab43acb3a4 118 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 119 MutexI2cWait.lock();
loopsva 0:2dab43acb3a4 120 #endif
loopsva 0:2dab43acb3a4 121
loopsva 0:2dab43acb3a4 122 int htu21 = 0;
loopsva 0:2dab43acb3a4 123 _i2c.start();
loopsva 0:2dab43acb3a4 124 htu21 = _i2c.write(HTU21Di2cWRITE); //i2c, 1 = ack
loopsva 0:2dab43acb3a4 125 if(htu21 == 1) {
loopsva 0:2dab43acb3a4 126 _i2c.write(HTU21DWRITEUSER);
loopsva 0:2dab43acb3a4 127 htu21 = _i2c.write(htu21data);
loopsva 0:2dab43acb3a4 128 _i2c.stop();
loopsva 0:2dab43acb3a4 129 }
loopsva 0:2dab43acb3a4 130
loopsva 0:2dab43acb3a4 131 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 132 MutexI2cWait.unlock();
loopsva 0:2dab43acb3a4 133 #endif
loopsva 0:2dab43acb3a4 134
loopsva 0:2dab43acb3a4 135 return(htu21);
loopsva 0:2dab43acb3a4 136 }
loopsva 0:2dab43acb3a4 137
loopsva 0:2dab43acb3a4 138 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 139 //Get the status of the heater the HTU21D user register. 0 = off, 4 = on.
loopsva 0:2dab43acb3a4 140
loopsva 0:2dab43acb3a4 141 uint8_t htu21d::getHeater() {
loopsva 0:2dab43acb3a4 142 uint8_t htu21data = htu21d::getUserReg();
loopsva 0:2dab43acb3a4 143 htu21data &= HTU21DHEATER;
loopsva 0:2dab43acb3a4 144 return(htu21data);
loopsva 0:2dab43acb3a4 145 }
loopsva 0:2dab43acb3a4 146
loopsva 0:2dab43acb3a4 147 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 148 //generic routine to get temp or humidity from HTU21D.
loopsva 0:2dab43acb3a4 149 //Returns 14 bits of data (anded 0xFFFC) or 0000 if i2c timeout occurs.
loopsva 0:2dab43acb3a4 150 //After a read temp or humidity command, HTU21D responds with NACKs until data is ready.
loopsva 0:2dab43acb3a4 151 //NOTE: Use non-hold commands
loopsva 0:2dab43acb3a4 152
loopsva 0:2dab43acb3a4 153 uint16_t htu21d::getData(uint8_t reg) {
loopsva 0:2dab43acb3a4 154 int htu21 = 0; //ACK flag
loopsva 0:2dab43acb3a4 155 int htu21cnt = 0; //number of NACKs before ACK or timeout
loopsva 0:2dab43acb3a4 156 uint16_t htu21data = 0; //returned data
loopsva 0:2dab43acb3a4 157
loopsva 0:2dab43acb3a4 158 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 159 MutexI2cWait.lock();
loopsva 0:2dab43acb3a4 160 #endif
loopsva 0:2dab43acb3a4 161
loopsva 0:2dab43acb3a4 162 _i2c.start();
loopsva 0:2dab43acb3a4 163 htu21 = _i2c.write(HTU21Di2cWRITE);
loopsva 0:2dab43acb3a4 164 _i2c.write(reg); //read temp, no hold
loopsva 0:2dab43acb3a4 165 if(htu21 == 0) return 0; //HTU21T not responding
loopsva 0:2dab43acb3a4 166 do {
loopsva 0:2dab43acb3a4 167 htu21cnt++;
loopsva 0:2dab43acb3a4 168 _i2c.start();
loopsva 0:2dab43acb3a4 169 htu21 = _i2c.write(HTU21Di2cREAD);
loopsva 0:2dab43acb3a4 170 if(htu21 == 1) {
loopsva 0:2dab43acb3a4 171 htu21data = _i2c.read(1) << 8;
loopsva 0:2dab43acb3a4 172 htu21data |= _i2c.read(0) & 0xFC;
loopsva 0:2dab43acb3a4 173 _i2c.stop();
loopsva 0:2dab43acb3a4 174 }
loopsva 0:2dab43acb3a4 175 wait_us(50);
loopsva 1:d3ed713f8354 176 } while((htu21cnt < 10000) && (htu21 == 0)); //htu21cnt takes 510 to get temp, 160 for humidity
loopsva 0:2dab43acb3a4 177
loopsva 0:2dab43acb3a4 178 #ifdef RTOS_H
loopsva 0:2dab43acb3a4 179 MutexI2cWait.unlock();
loopsva 0:2dab43acb3a4 180 #endif
loopsva 0:2dab43acb3a4 181
loopsva 0:2dab43acb3a4 182 if(htu21 == 0) return 0; //HTU21D ACK response timed out
loopsva 0:2dab43acb3a4 183 return(htu21data); //return 14 bit value
loopsva 0:2dab43acb3a4 184 }
loopsva 0:2dab43acb3a4 185
loopsva 0:2dab43acb3a4 186 double theTempIs = 0.0;
loopsva 0:2dab43acb3a4 187 double theHumIs = 0.0;
loopsva 0:2dab43acb3a4 188 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 189 //get temperature from HTU21D in degrees C. Returns with 255.0 if HTU21D had timed out.
loopsva 0:2dab43acb3a4 190
loopsva 0:2dab43acb3a4 191 float htu21d::getTemp() {
loopsva 0:2dab43acb3a4 192 uint16_t getData = htu21d::getData(HTU21DtempNOHOLD);
loopsva 0:2dab43acb3a4 193 if (getData == 0) return(255.0); //return with error
loopsva 0:2dab43acb3a4 194 double tempData = (double)getData / 65536.0;
loopsva 0:2dab43acb3a4 195 theTempIs = -46.85 + (175.72 * tempData);
loopsva 0:2dab43acb3a4 196 return(theTempIs);
loopsva 0:2dab43acb3a4 197 }
loopsva 0:2dab43acb3a4 198
loopsva 0:2dab43acb3a4 199 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 200 //get humidity from HTU21D in percentage. Returns with 255.0 if HTU21D had timed out.
loopsva 0:2dab43acb3a4 201
loopsva 0:2dab43acb3a4 202 float htu21d::getHum() {
loopsva 0:2dab43acb3a4 203 uint16_t getData = htu21d::getData(HTU21DhumNOHOLD);
loopsva 0:2dab43acb3a4 204 if (getData == 0) return(255.0); //return with error
loopsva 0:2dab43acb3a4 205 double tempData = (double)getData / 65536.0;
loopsva 0:2dab43acb3a4 206 theHumIs = -6.0 + (125.0 * tempData);
loopsva 0:2dab43acb3a4 207 return(theHumIs);
loopsva 0:2dab43acb3a4 208 }
loopsva 0:2dab43acb3a4 209
loopsva 0:2dab43acb3a4 210 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:2dab43acb3a4 211 //Calculate the Dew Point from getTemp and getHum. User must first execute both getTemp and getHum for an accurate result.
loopsva 0:2dab43acb3a4 212 //Calculations come from DHT library
loopsva 0:2dab43acb3a4 213 /* Copyright (C) Wim De Roeve
loopsva 0:2dab43acb3a4 214 * based on DHT22 sensor library by HO WING KIT
loopsva 0:2dab43acb3a4 215 * Arduino DHT11 library
loopsva 0:2dab43acb3a4 216 */
loopsva 0:2dab43acb3a4 217
loopsva 0:2dab43acb3a4 218 float htu21d::getDewPt() {
loopsva 0:2dab43acb3a4 219 // dewPoint function NOAA
loopsva 0:2dab43acb3a4 220 // reference: http://wahiduddin.net/calc/density_algorithms.htm
loopsva 0:2dab43acb3a4 221 double A0= 373.15/(273.15 + (double)theTempIs);
loopsva 0:2dab43acb3a4 222 double SUM = -7.90298 * (A0-1);
loopsva 0:2dab43acb3a4 223 SUM += 5.02808 * log10(A0);
loopsva 0:2dab43acb3a4 224 SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
loopsva 0:2dab43acb3a4 225 SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
loopsva 0:2dab43acb3a4 226 SUM += log10(1013.246);
loopsva 0:2dab43acb3a4 227 double VP = pow(10, SUM-3) * theHumIs;
loopsva 0:2dab43acb3a4 228 double T = log(VP/0.61078); // temp var
loopsva 0:2dab43acb3a4 229 return (241.88 * T) / (17.558-T);
loopsva 0:2dab43acb3a4 230 }
loopsva 0:2dab43acb3a4 231
loopsva 0:2dab43acb3a4 232 float htu21d::getDewPtFast() {
loopsva 0:2dab43acb3a4 233 // delta max = 0.6544 wrt dewPoint()
loopsva 0:2dab43acb3a4 234 // 5x faster than dewPoint()
loopsva 0:2dab43acb3a4 235 // reference: http://en.wikipedia.org/wiki/Dew_point
loopsva 0:2dab43acb3a4 236 double h21DtzA = 17.271;
loopsva 0:2dab43acb3a4 237 double h21DtzB = 237.7;
loopsva 0:2dab43acb3a4 238 double h21DtzC = (h21DtzA * theTempIs) / (h21DtzB + theTempIs) + log(theHumIs/100);
loopsva 0:2dab43acb3a4 239 double h21DtzD = (h21DtzB * h21DtzC) / (h21DtzA - h21DtzC);
loopsva 0:2dab43acb3a4 240 return (h21DtzD);
loopsva 0:2dab43acb3a4 241 }
loopsva 1:d3ed713f8354 242
loopsva 1:d3ed713f8354 243 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 1:d3ed713f8354 244 //Get the HTU21D serial number registers. Returns 64 bit register.
loopsva 1:d3ed713f8354 245 //should return 0x4854 00xx xxxx 32xx
loopsva 1:d3ed713f8354 246
loopsva 1:d3ed713f8354 247 void htu21d::getSNReg() {
loopsva 1:d3ed713f8354 248
loopsva 1:d3ed713f8354 249 #ifdef RTOS_H
loopsva 1:d3ed713f8354 250 MutexI2cWait.lock();
loopsva 1:d3ed713f8354 251 #endif
loopsva 1:d3ed713f8354 252
loopsva 1:d3ed713f8354 253 //get 16 bit SNC register, 8 bit SNC-CRC, 16 bit SNA register, 8 bit SNA-CRC
loopsva 1:d3ed713f8354 254 int htu21 = 0;
loopsva 1:d3ed713f8354 255 _i2c.start();
loopsva 1:d3ed713f8354 256 htu21 = _i2c.write(HTU21Di2cWRITE); //i2c, 1 = ack
loopsva 1:d3ed713f8354 257 if(htu21 == 1) {
loopsva 1:d3ed713f8354 258 _i2c.write(HTU21SNAC1);
loopsva 1:d3ed713f8354 259 _i2c.write(HTU21SNAC2);
loopsva 1:d3ed713f8354 260 _i2c.start();
loopsva 1:d3ed713f8354 261 htu21 = _i2c.write(HTU21Di2cREAD);
loopsva 1:d3ed713f8354 262 HTU21sn.HTU21D_snc = _i2c.read(1) << 8;
loopsva 1:d3ed713f8354 263 HTU21sn.HTU21D_snc |= _i2c.read(1);
loopsva 1:d3ed713f8354 264 HTU21sn.HTU21D_crcc = _i2c.read(1);
loopsva 1:d3ed713f8354 265 HTU21sn.HTU21D_sna = _i2c.read(1) << 8;
loopsva 1:d3ed713f8354 266 HTU21sn.HTU21D_sna |= _i2c.read(1);
loopsva 1:d3ed713f8354 267 HTU21sn.HTU21D_crca = _i2c.read(0);
loopsva 1:d3ed713f8354 268 _i2c.stop();
loopsva 1:d3ed713f8354 269 }
loopsva 1:d3ed713f8354 270
loopsva 1:d3ed713f8354 271 //get 32 bit SNB register, 32 bit SNB-CRC - regs are intermixed
loopsva 1:d3ed713f8354 272 htu21 = 0;
loopsva 1:d3ed713f8354 273 _i2c.start();
loopsva 1:d3ed713f8354 274 htu21 = _i2c.write(HTU21Di2cWRITE); //i2c, 1 = ack
loopsva 1:d3ed713f8354 275 if(htu21 == 1) {
loopsva 1:d3ed713f8354 276 _i2c.write(HTU21SNB1);
loopsva 1:d3ed713f8354 277 _i2c.write(HTU21SNB2);
loopsva 1:d3ed713f8354 278 _i2c.start();
loopsva 1:d3ed713f8354 279 htu21 = _i2c.write(HTU21Di2cREAD);
loopsva 1:d3ed713f8354 280 HTU21sn.HTU21D_snb = _i2c.read(1) << 24;
loopsva 1:d3ed713f8354 281 HTU21sn.HTU21D_crcb = _i2c.read(1) << 24;
loopsva 1:d3ed713f8354 282 HTU21sn.HTU21D_snb |= _i2c.read(1) << 16;
loopsva 1:d3ed713f8354 283 HTU21sn.HTU21D_crcb |= _i2c.read(1) << 16;
loopsva 1:d3ed713f8354 284 HTU21sn.HTU21D_snb |= _i2c.read(1) << 8;
loopsva 1:d3ed713f8354 285 HTU21sn.HTU21D_crcb |= _i2c.read(1) << 8;
loopsva 1:d3ed713f8354 286 HTU21sn.HTU21D_snb |= _i2c.read(1);
loopsva 1:d3ed713f8354 287 HTU21sn.HTU21D_crcb |= _i2c.read(0);
loopsva 1:d3ed713f8354 288 _i2c.stop();
loopsva 1:d3ed713f8354 289 }
loopsva 1:d3ed713f8354 290
loopsva 1:d3ed713f8354 291 #ifdef RTOS_H
loopsva 1:d3ed713f8354 292 MutexI2cWait.unlock();
loopsva 1:d3ed713f8354 293 #endif
loopsva 1:d3ed713f8354 294
loopsva 1:d3ed713f8354 295 }
loopsva 1:d3ed713f8354 296